Scientists recently announced the discovery of the prehistoric penguin, Kumimanu biceae, in a December 2017 study.

This species of penguin was previously unknown to scientists and it is one of the largest penguin fossils ever found. “Kumimanu” means “monster bird” in Maori, a native New Zealand language.

How big was this monster bird, you might ask?

This penguin is estimated to have been around 5 feet, 10 inches tall and weighed a whopping 220 pounds. The largest current living species of penguin, the emperor penguin, stands up to 44 inches (almost 4 feet) and weighs between 60 and 90 pounds.

So how did penguins get to be what they are today?

It is thought that the larger species of penguins, like K. biceae, existed shortly after penguins lost the ability to fly. K. biceae used to live on the east coast of New Zealand between 55 million and 60 million years ago.

A reconstruction of Kumimanu biceae as compared to a human diver | Photo credit: G. Mayr/Senckenberg Research Institute

Why did this large species exist in the first place?

K. biceae lived shortly after the Cretaceous-Tertiary mass extinction, 66 million years ago. After many dinosaurs went extinct during this period, there was an open niche for a large sea predator. This extinction event cleared the way for this giant penguin, yet the penguin was not the only species that evolved to fill this niche. One theory on why larger species of penguins did not survive is that they were outcompeted by marine mammals much larger than them like whales and seals. As they could not compete with them, they became smaller and more specialized for diving and catching smaller fish and crustaceans.

Penguin size comparison

The smallest species of penguin, the little blue penguin, stands at only 10-12 inches tall and weighs between 2 and 3 pounds. You can come see them right here at the New England Aquarium! It is hard to imagine a 3-pound penguin having evolved from a 220-pound penguin. It is likely that penguin species only reached “gigantic” sizes like K. biceae once, and all species after that continued to decrease in size. Penguins have been able to thrive currently in sizes from 10 to 44 inches and it is unlikely that they will evolve into giant species again so long as large marine mammals continue to roam the oceans.